Paper maker&#39;s drier felt



PAPER MAKERS DRIER FELT Filed Aug. 2, 1.938

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Patented Nov. 14, 1939 STATES .PTET

PAPER MAKER/S DRIER. FELT Thomas Hindle and Sam Lord, Blackburn, England2 Claims.

The invention relates to an improved construction of woven drier felt,as used on the drying cylinders of paper making machines, whereby thedrier felt will give more eicient and better drying of the paper, thatis to say, less steam will be required and the paper will be dried moreevenly across the width of the sheet.

The function of a drier-felt on a paper ma'- chine is to press the moistweb of paper uniformn ly and successively against the steam-heatedcylinders of the machine, thereby facilitating the transmission of heatfrom the cylinders to the paper for the purpose of drying the latter.

Drier ielts of known construction havea close homogeneous compacttexture, and Whilst moisture is readily absorbed from the paper, thepassage of air through the felt from one face to the other is veryrestricted. As a consequence, a drier-felt of such known constructionbecomes saturated, in which condition, as the moisture lls up the smallpores of the felt, it is even more impervious than when dry. Under theseconditions the drying of the paper is seriously retarded, and it isessential to maintain the cylinders at a higher temperature than wouldbe otherwise necessary, thus entailing a considerably higher steamconsumption.

Furthermore, moisture-laden air may be trapped forming pockets betweenthe paper and the felts, which pockets frequently prevent the paperbeing dried evenly across the width of the sheet.

To improve the drying of the paper, the drying sections of some papermachines are equipped with various systems of ventilation. In some oithese systems heated dry air is forced into the spaces', or some ofthem, between the paper, felts, cylinders, etc., and in others themoisture-laden air is extracted from those spaces. In either case, themaximum useful effect of such ventilation is not obtained owing to thehighly impervious nature of the drier felts of known construction.

The object of the invention is to provide a drier felt of greatlyincreased porosity, so as to permit air to pass very freely through thefelt from one face to the other, according to the particularrequirements of the ventilation system in use, but it will be understoodthat the improved drier-felt is also particularly advantageous if nospecial means for ventilation are available, inasmuch that naturalventilation is encouraged due to the pronounced porosity of thedrier-felt.

Since the air passes freely through the felt (ci. 13e-ics) it isprevented from becoming saturated and the drying of the paper is therebyaccelerated so permitting the cylinders to be operated at a lowertemperature with a resultant decrease in steam consumption. Moreover,owing to the lower temperature to which the felt is subiected its usefullife will be prolonged.

According "to the invention the drier felt is woven with two or morelayers having the warp and weft threads on face and back arranged ingroups, each group comprising at least three threads, such groups beinginterwoven so as to forni well-dened holes at the points where theyintersect and so that these holes shall coincide in both or all layersof the drier-felt the weft threads of each group in one layer are invertical alignment with those oi the corresponding group or groups inthe other layer or layers and the threads oi the warp groups whichinterweave therewith are similarly in vertical alignment.

In the case of a two-layer drier-felt, the two layers may be boundtogether by an additional intermediate layer of weit, which layer mayconsist of the same number oi weit threads as Vused to form the face andback layers, or alternatively may consist of a smaller number. f

The invention will be described with reference to the accompanyingdrawing in which Fig. 1 is a View showing the appearance of the face andof the back of a felt woven in accordance with the invention.

Fig. 2 is a diagrammatic longitudinal section across the weft of atwo-layer drier felt in which the surface weft threads and the warpthreads are divided into groups of three and one binder weit is employedfor a group of three wefts on each surface.

Fig. 3 is a diagrammatic transverse section across the warp of the twolayer drier felt shown in Fig. 2.

Fig. 4 is a diagrammatic longitudinal section across the weft of atwo-layer drier telt in which the surface weft threads and the warpthreads are divided into groups of three, and two binder wefts areemployed for a group of three wefts on each surface.

Fig. 5 is a diagrammatic transverse section across the warp of the twolayer drier felt shown in Fig. s.

Fig. 6 is a diagrammaticlongitudinal section across the weft of atwo-layer drier felt in which the surface weft threads and the warpthreads are divided into groups of three and three binder wefts areemployed for a group of three weits on each surface.

Fig. 7 is a diagrammatic transverse section through the warp of the twolayer drier felt shown in Fig 4.

In the weave illustrated in Figs. 2 and 3 for each repeat there aretwelve individual' Warp threads a, i. e., four groups each of threethreads and fourteen weft threads b, i. e., four groups each of threethreads and two binder threads, one for each pair of groups of surfacethreads. The warp threads are designated la, Za-IZE, and the weftthreads lb, ZL-Mb, the threads 4 and Illo being the binder threads.

As will be seen from Figs. 2 and 3, the rst group of weft threads lb, 3band 6b and the third group 8b, lill and 3b form one surface of the feltand the second group 2b, 5b and 'lb and fourth group 9b, i2b and Mb, theother surface, the rst and third groups interweaving with the rst groupla, 3EL and 5P- and the third group 1a, 9a and Ila of the warp threadsand the second and fourth group with the second group 2a, 4a, and 51Land fourth group 8a, Illa and I2a of the warp threads. The binder weft4b being woven alternately with the first and fourth groups of warpthreads and the binder weft Hb with the second and third groups thereof.Neither of the binder wefts lib and lib appear on the surfaces of thefelt but lie between each pair of groups of the three surface threads.

The weave illustrated in Figs. 4 and 5 is similar to that shown in Figs.2 and 3 except that four binder weft threads 3b, 5b, lib and I3b areemployed, the threads 3b and 5b following one path and the threads Hband i3b the alternate path. As before the twelve warp threads aredivided into four groups la, 3a and 5a; 2a, lr1 and Ga; la, 9a and lla;and 83, lila and i221 whilst the twelve weft threads forming thesurfaces of the felt are divided into four groups Ib, 4b and 1b; 2b, 6band Sb; 9b, l2b and 15b; and 10b, Mb and I6b respectively. None of thebinder wefts 3b, 5b, Hb or I3b appear on the surfaces of the felt butlie between each pair of groups of the three surface threads.

The weave illustrated in Figs. 6 and 7 is similar to that shown in Figs.2 and 3 and Figs. 4 and 5 except that six binder weft threads 2b, 5b,8b, IIb, Elib and l'lb are employed, the threads 2b, 5b and 8b followingone path and the threads I lb, Mb and iib the alternate path. As beforethe twelve warp threads are divided into four groups la, 3a and a; 2a,4a and 5a; la, 9a and Ila; and 8a, Illa and I 2a whilst the twelve weftthreads forming the surfaces of the felt are divided into four groupslb, Gb and 1b; 3b, '6b and 9b; 10b, I3b and 18h; and 2b, I 5b and Ibrespectively. None of the binder wefts 2b, 5b, 3b, Hb, |11b and l'lbappear on the surface of the felt but lie between each pair of groups ofthe three surface threads.

Instead of the weft threads and warp threads being divided into groupsof three they may be divided into groups of four or more in which casethe number of binder weft threads for each pair of groups may be anynumber from one up to the number of threads in a group.

A felt woven as hereinbefore described produces a pronounced hole a: ateach of the points where the groups of Warp a and weft b intersect andthe formation of these holes may be assisted by reeding the Warp withsiX warp threads per dent, i. e., the warp threads forming each pair ofgroups. If each group contains four warp threads then they could bereeded eight threads per dent and so on. This however is not essential,as the interweaving of the weft causes the grouping of the warp threadsand the interweaving of the Warp causes the group of the weft threads onthe face and back.

In a felt woven according to the invention there is no tendency for thegroupings of the warp and weft threads to be lost and Consequently whenthe drier felt is running on the paper machine the holes a: will not beremoved.

The improved drier-felt may be woven from vegetable, animal, mineral orartificial threads, or any combination thereof, according to particularrequirements.

What we claim as our invention and desire to protect by Letters Patentis:

1. A two layer drier felt comprising groups of weft threads and groupsof warp threads on the face and back, the threads of each group lyingcontinuously in side by side relationship and each group containing thesame number of threads and at least three, the groups of weft threads ofthe face being interwoven with the groups of warp threads of the faceand the groups of weft threads of the back being interwoven with thegroups of warp threads of the back and the groups of each layer being invertical alignment with those of the other layer whereby well definedcoinciding vertical holes are formed at the points where the groups ofweft threads intersect the groups of the warp threads and a plurality ofintermediate binding weft threads not greater in number than the threadsin each surface group, for binding the two layers together which bindingweft threads do not appear on either surface but lie between the surfacegroups each binding thread lying in the same perpendicular plane as apair of weft threads in the top and bottom surfaces respectively so thatit will not obscure any of the vertical holes.

2. A two layer drier felt comprising groups of weft threads and groupsof warp threads on the face and on the back, the threads of each grouplying continuously in side by side relationship and each groupcontaining three threads, the threads both weft and warp of one group ofone surface being in vertical alignment with the corresponding group ofthe other surface whereby on interweaving the weft and warp groups ofeach surface well dened Vertical holes are formed, the holes in eachsurface being in alignment and binder weft threads of a number notgreater than three which do not appear on either surface but lie betweenthem the threads of each group lying continuously in side by siderelationship,

'THOMAS HINDLE. SAM LORD.

